D 5505 Safely removing injectors / nozzles

[evranch_canada]

Good evening,

I have seen several threads here about removing injectors, but in them, there was often debate and argument, and sometimes injectors being damaged or warnings about damage. It appears like it should be simple, but why is there so much debate and warnings?

I have the 812 service manual, I am familiar with diesel injectors. I have disassembled, cleaned and rebuilt them from tractors such as Case and Massey, but not this style.

So first I need to loosen the 30mm nut. This is not really a nut, but a hollow bolt that is threaded into the head, retaining the injector assembly. No special tool, just a big wrench.

Then, I can simply remove the injector assembly from the head, pull it straight out. Something remains in the head that may need to be removed with a slide hammer... I have read comments saying it is the nozzle. But it doesn't appear to be the nozzle DN0SD, as this is held on with the union nut? What is it that is supposed to remain in the head? I don't see anything on the picture to be left behind. Or do you slide hammer the entire assembly if it is stuck with carbon?

I especially want to avoid the situation that happened to Harm long ago in this thread and was trying to understand what happened there. It appears the 30mm nut was destroyed, then the union nut unscrewed from KD45 and was left behind with DN0SD nozzle. This came apart because of twisting KD45 relative to the head, while the union nut was still retained inside by the 30mm nut? At least the damaged parts are supplied with the injector as long as you don't ruin the threads in the head, it looks like.

Finally the cracking pressure is set by adjusting the set screw underneath the leak-off pipe, which compresses an internal spring. As long as I don't disassemble or twist this part of the injector, the cracking pressure should not be changed. However if I need to remove the union nut, change DN0SD, or otherwise twist the main injector body and move the spring, I will need to use a pressure tester to reset the cracking pressure. Correct?

Also, what is that piece sticking out of the fuel inlet? Sometimes it's there and sometimes not in the manual, but it's there on my tractor. No documentation. Meant to damp noise or something? Safe to remove and clean it out?

Thank you again for your help, and especially if you took the time to read all this,
Alex

 

[Deutz45nullfuenf]

was trying to understand what happened there.

Hi Alex,
i believe that the injectors were sitting there since 1966. So it was due to corrosion that they did not come out. If regular maintenance is done to these parts (which is not the case on most of the tractors) this would not happen. They just run until something is dead and that happens after 50 years of use.
I think you have to use a large amount of rust remover (? is that the right word) and not WD40! This needs time to creep into the thread.

 

[swd40]

Hi,

there's a video from steelstyler on Youtube for removing the nozzle holder (injector holder, 'Düsenhalter' or 'Düsenstock' in german) on his D30s with 812 injectors.

The injector holder is screwed together as one part and the 30mm nut just presses it down. As long as the nut is moving fine in the threads it will easily pull out the whole injector holder. If not you should loosen it carefully (turn left and right, use rust remover .... maybe warm it up ... ). If not that may damage the threads inside the cylinder head and you would need a new one.

Below the injector holder there is a washer (sealing ring or heat insulating plate, 'Flammscheibe' or 'Wärmeschutzplatte' in german). This is not a copper ring as in the 612/712 injector holders but some more durable material. There is a tool for extracting this washer but usually you may just pick it out. Just don't scratch on the metal base where the washer fits on, that may lead to losing compression there.

If you have removed the injector holder you can screw open the whole thing to get to the injector.

The long thing that is on the injector line is a filter. This is a metal filter with some plates inside so that dirt would not get to the injector. I haven't seen that open yet. But I also haven't seen that on 812 motors, just on 712 ones with the older injector holder. But if it's there it may need some blow from an air hose to be cleaned.

Regards,

Josef

 

[Oggy]

This is a 812 Flammscheibe
Flammscheibe Deutz 812 Hitzescheibe Wärmeschutzscheibe Einspritzdüse

Best Regards

 

[evranch_canada]

Hello all,

Harm, this is the main concern I have for mine as well, especially after removing stuck glow plugs to find ancient plugs with no anti-seize, graphite etc. So I think they will be hard. 30mm nut shows no sign of moving at all.

Real mechanics here don't use WD40 either! I like to mix automatic transmission fluid with acetone to make a very thin oil that soaks deeply into threads. Using a torch will help drive it in further by boiling the acetone, it's very effective.

I got the glow plugs out by soaking 2 days with this oil mixture, then idling with the air chamber open until the heads were hot. Then high speed, low power impact gun to shake them out, unfortunately not an option with these injector nuts.

It turns out I don't even have a 30mm wrench that is not a socket, so I will have to buy one next trip to the city. Adjustable wrench will just round them off, I know.


Josef, thanks for this video! It shows exactly what I wanted to see, that the 30mm "nut" actually jacks the injector out, and what comes out with it. I searched Youtube myself for videos, but it is humbling for an English speaker to see that there is a whole other Internet that I never even knew about.

If that thing is a filter then they may well be plugged. The reason I'm pulling injectors is that when I had the glow plugs out, I did the test where you allow diesel to puff out, and it is definitely uneven despite the tractor running "well". Thermal scanning also showed 1 cylinder working harder. Though looking at what is considered "running well" for Deutz here, all my tractors need work. Me and my neighbours all expect an old diesel to clatter, but it appears even old Deutz can purr like a kitten.

After seeing one hot cylinder, I bled injector lines and some air was released. Significant improvement but still, rear cylinders are carrying the load. All cylinders are firing and loosening nuts shuts them off, but clearly fuel delivery is uneven. It's surprising it runs as well as it does.


Oggy, thanks for the link to the Flammscheibe, now I know what to expect. Cheap! As are DN0SD nozzles. But I will leave them in there for now, and order some to replace them. Once the injectors have been removed once, they should be easy to pull again to change these.


Thanks again to everyone for sharing your knowledge with me!

Alex

 

[FahrM66Tfan]

Good afternoon,

To screw out those stuff i use technical ice spray that makes it possible to cool down those parts about 40 degrees minus. So they become loose in a short time. There is no need to wait two days or soaking them with anything that maybe will help.

Friedrich

 

[Kai6.05]

Hi Friedrich,

how many hardly stuck injectors did you disassemble with this procedure?

Kind regards, Kai

 

[evranch_canada]

So the planned procedure worked perfectly, soaked the threads with oil/acetone and then today I idled with the air chamber open until the heads reached over 100C. Then a light tap on the wrench was all it took to break them free, they came out completely intact with no struggle.

Filthy carbon and bad spray pattern though, I soaked them in solvent and then cleaned the faces with a rag, didn't disassemble them as I don't own a tester to set the pressures. Maybe I should buy a cheap one as I could check and set injector pressures on other old tractors as well.

I coupled them up and ran the starter to blow diesel into the air, now they all appear to be spraying nice jets that create a mist. Without a proper test stand it's hard to see if they're all equal, but they're much better than they were. Time to clean off those Flammscheibe which are also covered in carbon, and reinstall and test.

That "filter" piece is very hard to get air to blow through. But I'm quite hesitant to attempt to disassemble one. One end has a core like a tire valve, the other is a flat face to seal to the injector, no apparent way to disassemble aside from loosening the core. It looks a bit more complex than a filter should be.

If we want to cool parts to -40C we can just leave them outside in winter... but then the whole tractor is -40C, and things are worse However working on a cold day makes it easy to generate big temperature differentials with the torch, sometimes this works well on things like steering parts.

At a shop I worked at years ago, we would use dry ice to shrink parts, but I now live too far from the city to get any. Dry ice was amazing to use for any type of internal sleeve, both to remove or to install. No press, just drop it in!

Alex

 

[evranch_canada]

Quick question for those who have worked on these injectors. Is DN0SD nozzle supposed to have a completely flat face, or a small indent in the middle around the needle?

Pictures online look flat. Mine all have a little "crater" in the middle where they would have been exposed to combustion.

I reinstalled them and test ran the tractor, it will now idle very low and quiet, and will rev up faster and smoother. But exhaust temperatures are still uneven, and there is still a bit of clatter. I think I should test and set cracking pressure at least, possibly replace nozzles.

 

[Kai6.05]

Hi alex,

watch out! The needle is proud of the surface in the middle. You can easily damage the needle if you clean it by scrubbing.

Maybe you could interchange the injectors of the cilinders and have a look at the temperatures again. If the temp difference is a cause from the injectors, the Error would "wander" around.

Greetings, Kai

 

[Oggy]

Moin, I replaced the DNOSD , it has a flat surface with the tip of the needle looking 1mm out.
https://www.deutzforum.de/attachments/koepfe_fl812-fl812s-jpg.199186/



Best Regards Andreas

 

[evranch_canada]

Thanks Kai, that's a good idea to swap them around and see the heat follows the injectors. As well as for the warning, but don't worry as I know how to deal with pintle injectors with the projecting needle, I'm just not familiar with this wide and fat nozzle design. I cleaned them carefully with a twisting motion around the needle and with dental tools to dislodge carbon flakes.

However looking at that picture, Oggy, mine definitely are not flat like that, they have an erosion crater in the middle around the needle. Maybe 5-20 thou deep and different on each one (not sure what the equivalent metric tiny measurement is?). As this likely affects the seal on the needle and thus the spray pattern, I'll plan to replace them, especially as they are quite cheap. They are probably the original nozzles.

Thanks,
Alex

 

[evranch_canada]

So the heat did not follow the injectors. But the replacement gauge for my compression tester showed up.

340, 330, 360, 370 psi (23-25 bar) with 330 being the hottest cylinder. Also now that it's clean, I noticed there is a bit of exhaust gas puffing at the head/cylinder seal on the cylinder furthest to the rear (340 psi) when running. Probably should pull it off and try to lap it. Or does it make sense to simply loosen and retighten the head bolts first?

Valves were all adjusted when I bought the tractor and I rechecked them last week.

Is lower compression a good explanation for this temperature difference? I know many of you are much more knowledgeable than me, so correct me if I'm wrong here. Lower compression makes diesel burn slower in that cylinder, resulting in more energy lost as exhaust heat instead of converted to work?

The tractor does start and run well enough for farm work, I just like to maintain my equipment in the best condition as I can, without spending lots of money or searching for rare parts. On a water cooled tractor this likely wouldn't even be noticeable... I don't like the wide compression pressures, but should I just try to get that first head sealed up and then let it be?

Thanks, Alex

 

[Kai6.05]

Hi Alex,

so you have 23; 22; 25; 26bar. This is quite a bigger difference than I would expect. The 330psi should stay the coldest... Could you test again to see if the device is correct?

Greetings, Kai

 

[evranch_canada]

Hi Kai,

I was surprised myself, so did multiple tests to confirm. Each cylinder was sampled twice in a row, and then I did 2 sweeps across the bank. i.e. 1234 4321 to ensure the results were not affected by oil control or heat of compression. The battery was connected to a powerful old-style charger for constant cranking speed. Total of 4 samples per cylinder, all results were consistent. All glow plugs were removed, of course.

That was my initial thought too, like in a gas engine the lowest pressure should be cold and sooty due to weak combustion. That's why I was wondering if in an indirect diesel, is it possible that lower compression results in effective timing retard as the pressure rises later?

I've worked more with direct injection and am not sure on the exact dynamics of injection timing with pre-combustion chambers. I have read that sometimes the injector can actually spray before ignition pressure is reached, depending on chamber design. Maybe not in these engines though, this is my only 812, you would know better than me! I am here to learn.

Alex